Process for the production of a lightweight cold urethane

ABSTRACT

In a process for the production of a lightweight cold urethane wherein raw materials are injected into a mold in one shot, diethanolamine is added in an amount of 0.1 to 2.0 parts by weight per 100 parts by weight of the polyol. When principal raw materials including a polyol and an isocyanate, and an auxiliary ingredient mixture prepared by previously mixing auxiliary ingredients other than the polyol and the isocyanate, are injected into a mold from separate storage vessels, a water-soluble silicone foam stabilizer is added to the auxiliary ingredient mixture.

FIELD OF THE INVENTION

[0001] This invention relates to a process for the production of alightweight cold urethane which is a raw material for cushioningmaterials used in the seats of automobiles, motorcycles and the like.

BACKGROUND OF THE INVENTION

[0002] Conventionally, urethane foam is used, for example, in the seats81 and 82 of an automobile 80 illustrated in FIG. 8. Automobile seats 81and 82 are classified into front seats 81 and rear seats 82. Asillustrated in FIG. 9, each of seats 81 and 82 consists of a cushionedpart 83 which supports one's buttocks directly, and a backrest 84against which one's back is leaned. Roughly speaking, each seat is madeup of four components as illustrated in FIG. 9. They include a frame 83a or 84 a providing the framework of the seat, springs 83 b or 84 b formaintaining cushioning properties, urethane 83 c or 84 c serving toabsorb vibrations, and a skin 83 d or 84 d protecting the urethane andcoming into direct contact with one's body. Among such urethanes 83 cand 84 c, especially the urethane 84 c constituting the backrests isrequired to have softness and holding properties.

[0003] A lightweight cold urethane is especially suitable for use as theurethane constituting the backrests (i.e., back urethane).

[0004] However, conventional lightweight cold urethanes had thefollowing problems.

[0005] (1) Conventional lightweight cold urethanes have a density ofabout 40 kg/m³ and are heavier than hot urethanes (27-35 kg/m³). Theyrequire a larger number of raw materials to be injected into a mold, andhence involve a high cost. Moreover, they cause a corresponding increasein car body weight and hence bring about poor fuel consumption.

[0006] (2) In conventional formulations, the density can be reduced tosome extent (34 kg/m³) by increasing the amount of water (i.e., thenumber of parts of water). However, this causes a problem in that theresulting urethane no longer has flame retardancy. Although the additionof a flame retardant is conceivable, this causes an increase in cost andis hence impractical. Moreover, the resulting urethane gives an easilyyielding pad and fails to meet performance requirements for seats.

[0007] As a lightweight cold urethane solving these problems and meetingproperty requirements such as excellent flame retardancy, the presentinventors developed a lightweight cold urethane as disclosed in JapanesePatent Provisional Publication No. 10-176025. However, this lightweightcold urethane still has an unsolved problem in that the type of polyolused is limited.

[0008] Accordingly, there is a need for the preparation of a lightweightcold urethane having a flame-retardant formulation using common polyols.Additional urethane formulations are described in Japanese PatentProvisional Publication Nos. 5-320304, 6-166042 and 5-202164. However,none of them can bring about an improvement in flame retardancy.

[0009] On the other hand, it has been conventional practice to feed twourethane-forming raw material fluids from raw material fluid sourcesinto an injection head through separate hoses, and inject them from theinjection head into a lower mold section. Both fluids are mixed bycollision in the injection head and then injected into the mold.Moreover, such a two-component foaming mold has been developed so as touse a four-component injection head. This permits various types ofurethane foam having different densities and hardnesses to be formedwith a single injection head.

[0010] When such an injection head is used, it is preferable that, amongvarious compounding ingredients, auxiliary ingredients be mixed andplaced in one working tank. However, in conventional formulations, thisauxiliary ingredient mixture consists chiefly of water. This has beenproblematic in that the piping is apt to rust and a homogeneous fluidcannot be formed because of the poor miscibility of water and an oilysilicone foam stabilizer or the like. For this reason, even the use of afour-component injection head has been unable to produce satisfactoryresults.

SUMMARY OF THE INVENTION

[0011] Accordingly, an object of the present invention is to provide aprocess for the production of a lightweight cold urethane having aflame-retardant formulation using common polyols. Another object of thepresent invention is to provide such a process for the production of alightweight cold urethane by using a formulation with which, even when afour-component head is used, the piping can be prevented from rustingand the uniform dispersion of auxiliary ingredients can be achieved.

[0012] In accordance with the present invention, there is provided aprocess for the production of a lightweight cold urethane, whichcomprises the steps of adding diethanolamine to the formulation in anamount of 0.1 to 2.0 parts by weight per 100 parts by weight of a polyoland injecting raw materials into a mold in one shot.

[0013] In the process for the production of a lightweight cold urethanein accordance with the present invention, it is preferable thatprincipal raw materials including a polyol and an isocyanate, and anauxiliary ingredient mixture prepared by previously mixing ingredientsother than the polyol and the isocyanate, be each injected from separatestorage vessels into a mold, and that a water-soluble silicone foamstabilizer be added to the auxiliary ingredient mixture.

[0014] In the process for the production of a lightweight cold urethanein accordance with the present invention, it is preferable that the rawmaterials include 100 parts by weight of a polyol, an isocyanate used inan amount in the range of 70 to 150% of its stoichiometric amount forthe polyol, and an auxiliary ingredient mixture comprising 2.5 to 5.5parts by weight of water, 0.1 to 2.0 parts by weight of diethanolamine,0.5 to 3 parts by weight of a catalyst, 0.4 to 2.0 parts by weight of awater-soluble silicone foam stabilizer, 0 to 2.0 parts by weight of asilicone foam stabilizer, and other additives. Moreover, the auxiliaryingredient mixture may further comprise a rust preventive, preferably inan amount of not greater than 0.1 part by weight.

[0015] Furthermore, in the process for the production of a lightweightcold urethane in accordance with the present invention, the aforesaidauxiliary ingredient mixture may further comprise a polyol. In thiscase, it is preferable to add a polyol to the aforesaid auxiliaryingredient mixture in an amount of 0 to 50 parts by weight per 100 partsby weight of the polyol fed to the mixing head as a principal rawmaterial by way of another system.

[0016] When parts and percentages are used herein to express amounts andproportions, they are by weight unless otherwise specified.

[0017] As will become evident from the following description, thepresent invention provides a process for the production of a lightweightcold urethane having a flame-retardant formulation using common polyols.Moreover, the present invention also provides a process for theproduction of a lightweight cold urethane by using a formulation withwhich, even when a four-component head is used, the piping can beprevented from rusting and the uniformed dispersion of auxiliaryingredients can be achieved.

[0018] Other objects, features, and advantages of the present inventionwill be apparent from the accompanying drawings and detailed descriptionthat follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is illustrated by way of example and not byway of limitation in the figures of the accompanying drawings. In theaccompanying drawings similar references indicate similar element.

[0020]FIG. 1 is a graph showing the relationship between the amount ofdiethanolamine added and the flame retardancy, with regard to theprocess for the production of a lightweight cold urethane in accordancewith the present invention.

[0021]FIG. 2 is a schematic view showing the relationship between thefoam formed and its crosslinked points and cell skeleton, with regard tothe process for the production of a lightweight cold urethane inaccordance with the present invention.

[0022]FIG. 3 is a schematic view for explaining a state in which thefoam formed undergoes a rupture of cell membrane, with regard to acommon process for the production of a lightweight cold urethane.

[0023]FIG. 4 is a perspective view illustrating one embodiment of aurethane foaming mold which can be used in the process for theproduction of a lightweight cold urethane in accordance with the presentinvention.

[0024]FIG. 5 is a perspective view illustrating an air sequence box foruse with the urethane foaming mold of FIG. 4.

[0025]FIG. 6 is a flow chart showing a series of steps for producingurethane foam for automobile seats by using the urethane foaming mold ofFIG. 4.

[0026]FIG. 7 is a plane view illustrating a seat manufacturing equipmentequipped with mold carriers each having the molds of FIG. 4 attachedthereto.

[0027]FIG. 8 is a perspective view illustrating one embodiment of anautomobile to which the urethane products made according to the presentinvention can be applied.

[0028]FIG. 9 is a perspective view for explaining the construction of anautomobile seat.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] In the process for the production of a lightweight cold urethanein accordance with the present invention, diethanolamine is added to theformulation in an amount of 0.1 to 2.0 parts by weight per 100 parts byweight of the polyol. For example, raw materials are compoundedaccording to the formulation shown in Table 1. TABLE 1 Compounding ratio(by Raw materials weight) Fluid A Polyol (PPG + POP) 100 Crosslinkingagent 0.1-2.0 (diethanolamine) Catalyst (e.g., TEDA-L33) 0.5 Catalyst(e.g., TOYOCAT-ET) 0.1 Silicone foam stabilizer A 0-3 Silicone foamstabilizer B 0-3 Foam breaker  0-10 Other auxiliary ingredients  0-10Foaming agent (H₂O) 2-6 Fluid B Isocyanate 90-110% of the stoichiometricamount

[0030] In this formulation, the polyol preferably comprises acombination of PPG such as HIFLEX 515 (trade name; manufactured byDai-ichi Kogyo Seiyaku Co., Ltd.) and POP such as HIFLEX ND853 (tradename; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.). These PPG andPOP are stored in separate working tanks (storage vessels) and fed tothe injection head through separate pipe lines. PPG is prepared by theaddition polymerization of propylene and ethylene to glycerol or thelike. The polyol prepared by the graft polymerization of polystyrene orthe like to PPG is called POP or a graft polyol.

[0031] The ingredients of fluid A other than the polyol are mixed toprepare an auxiliary ingredient mixture. This auxiliary ingredientmixture is stored in a separate working tank and fed to the injectionhead. This auxiliary ingredient mixture may contain a polyol.

[0032] Useful catalysts include amine catalysts such astriethylenediamine, bis(2-dimethylaminoethyl) ether,1,4-diazobicyclo[2.2.2]octane, N,N,N′,N′-tetramethylhexamethylenediamineand N,N,N-tris(dimethylaminopropyl)amine. Moreover, there may also beused other types of catalysts (e.g., organotin compounds) or acombination of some catalysts, so long as the urethane product desiredin the present invention can be obtained.

[0033] In the present invention, a silicone foam stabilizer may also beused as an additive.

[0034] This additive is used to facilitate the mixing and emulsificationof the polyol, water and the isocyanate and stabilize the foam beingformed.

[0035] Specifically, it is preferable to use a compound of the followingformula (I) in which polyether groups are joined to a dimethylsiloxanechain as pendant groups.

[0036] In formula (I), a, b, m and n are independent integers of 0 orgreater respectively. R′ is a hydrocarbon chain interposed between Siand O (oxygen atom), and may be a saturated, unsaturated, branched orlike hydrocarbon chain. R is an alkyl group and may be a saturated,unsaturated, branched or like alkyl group.

[0037] The foam breaker is added for the purpose of breaking the cellwall of the urethane foam to form interconnected cells and therebyenhancing the air permeability of the urethane foam. A specific examplethereof is DK FLEX 800 (trade name; manufactured by Dai-ichi KogyoSeiyaku Co., Ltd.).

[0038] As other auxiliary ingredients, a crosslinking agent and a flameretardant may be added.

[0039] Water is added as a foaming agent.

[0040] Preferred examples of the isocyanates which can be used in thepresent invention include aromatic polyisocyanates.

[0041] More preferably, a mixture composed of TDI (tolylenediisocyanate) represented by the following formula (II) and p-MDI(polymethylene polyphenyl polyisocyanate) represented by the followingformula (III) is used.

[0042] The isocyanate is stored, as fluid B, in a working tank otherthan the aforesaid three working tanks.

[0043] When a mixture of TDI and p-MDI is used, the weight ratio of TDIto p-MDI (TDI/p-MDI) is preferably in the range of 80/20 to 100/0.

[0044] The amount of isocyanate used is in the range of 80 to 120% ofits stoichiometric amount for the polyol.

[0045] A specific example of the formulation of Table 1 is shown inTable 2. Using this formulation, changes in flame retardancy wereexamined by adding 1 to 10 parts by weight of diethanolamine. Theresults thus obtained are shown in FIG. 1. TABLE 2 Compounding ratio (byRaw materials Manufacturer weight) Fluid A Polyol (PPG + POP) AsahiGlass 100 Co., Ltd. Crosslinking agent Mitsui 0.5 (diethanolamine)Chemicals, Inc. Catalyst (TEDA-L33) Tosoh 0.5 Corporation Catalyst Tosoh0.1 (TOYOCAT-ET) Corporation Silicone foam Nippon Unicar 1.0 stabilizer(SZ-1311) Co., Ltd. Silicone foam Nippon Unicar 1.0 stabilizer (L-5366)Co., Ltd. Foam breaker (DK Dai-ichi Kogyo 4.0 FLEX 800) Seiyaku Co.,Ltd. Foaming agent (H₂O) 4.5 Fluid B Isocyanate (TM-20) Mitsui 55.0Chemicals, Inc.

[0046] It can be seen from FIG. 1 that, when no diethanolamine is added,the urethane foam is not incombustible. When diethanolamine is added,the number of crosslinked points 102 between cells 101 increases asillustrated in FIG. 2. Owing to the increase of crosslinked points 102,the cellular skeleton 103 of the urethane foam comes to have a higherdensity. The increase in density causes a decrease in the degree ofcontact with air, resulting in a reduction in burning rate and hence animprovement in flame retardancy. Eventually, the urethane foam becomesincombustible when the amount of diethanolamine added reaches 0.1 partby weight. As diethanolamine is added in greater amounts, the increasein the density of the cell skeleton and the reduction in burning rate(hence the improvement in flame retardancy) proceed further.

[0047] However, the addition of diethanolamine not only increases thedensity of the cell skeleton, but also enhances the air permeability ofthe foam. The reason for this is that the cell membrane becomes thinnerand hence undergoes a rupture 104 (FIG. 3). The enhancement in airpermeability decreases combustion-inhibiting factors and, moreover,increases contact with air, so that the urethane foam becomescombustible. When diethanolamine is added in greater amounts, such airpermeability is manifested and, therefore, the once reducedcombustibility begins to increase gradually.

[0048] That is, while the increase of the density of the cell skeletondominates, the foam remains incombustible. However, when the amount ofdiethanolamine added is increased to such an extent that the airpermeability factor dominates, the foam ceases to be incombustible. Thissituation can be understood by reference to FIG. 1.

[0049] As can be seen from the above description, the amount ofdiethanolamine added is preferably in the range of 0.1 to 2 parts byweight per 100 parts by weight of the polyol.

[0050] Moreover, in another embodiment of the present invention, awater-soluble silicone foam stabilizer is used in the formulation. Anexemplary formulation is shown in Table 3. Formulation Raw materialsCompounding ratio (by weight) H₂O 2.5-5.5 Diethanolamine 0.1-3.0Catalyst 0.5-3.0 Water-soluble silicone foam 0.4-2.0 stabilizer Siliconefoam stabilizer   0-2.0 Rust preventive   0-0.1 Other additives  0-10Polyol 100 Isocyanate 70-150% of the stoichiometric amount

[0051] According to this embodiment, even if only the auxiliaryingredients shown in Table 3 are used, no rust is formed because of animprovement in the dispersibility of the auxiliary ingredients.

[0052] Its difference from the formulation of Table 1 lies in the factthat a water-soluble silicone foam stabilizer is added and a rustpreventive is added as required.

[0053] Similarly to the formulation of Table 1, the polyol may comprisePPG such as HIFLEX 515 (trade name; manufactured by Dai-ichi KogyoSeiyaku Co., Ltd.) and POP such as HIFLEX ND853 (trade name;manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.). Alternatively, thepolyol may comprise PPG such as XF-8387 (trade name; manufactured byAsahi Glass Co., Ltd.) and POP such as EL-946 (trade name; manufacturedby Asahi Glass Co., Ltd.). PPG and POP are stored in separate workingtanks and fed to the injection head through separate pipe lines.

[0054] The ingredients of fluid A, other than the polyol, are mixed toprepare an auxiliary ingredient mixture. This auxiliary ingredientmixture is stored in a separate working tank and is fed to the injectionhead.

[0055] Diethanolamine, the catalyst, the silicone foam stabilizer andthe other additives may be the same as those described in theformulation of Table 1.

[0056] As the water-soluble silicone foam stabilizer, a mixture composedof a polyoxyalkylene-dimethylpolysiloxane copolymer of the followingchemical formula and a polyoxyethylene alkyl ether, such as SZ-1333(trade name; manufactured by Nippon Unicar Co., Ltd.), may be used.

(CH₃)₃SiO—[(CH₃)₂SiO]_(m)—[CH₃SiO][C₃H₆O(C₂H₄O)_(a)(C₃H₆O)_(b)R]_(n)—Si(CH₃)₃—C_(n)H_(2n)+10(C₂H₄O)_(a)H

[0057] As the rust preventive, a mixture of a phosphoric acid salt,hydrazine and an alkaline agent, such as Aquas Chelate MC-111 (tradename; manufactured by Aquas Corporation), may be used.

[0058] The isocyanate is stored, as fluid B, in a working tank otherthan the aforesaid three working tanks.

[0059] When a mixture of TDI and p-MDI is used, the weight ratio of TDIto p-MDI (TDI/p-MDI) is preferably in the range of 80/20 to 100/0.

[0060] The amount of isocyanate used is in the range of 70 to 150% ofits stoichiometric amount for the polyol.

[0061] In the process for the production of a lightweight coldpolyurethane in accordance with the present invention, molding iscarried out by maintaining the mold temperature at a temperature of 20to 80° C. In the case of a hot urethane, molding is carried out byheating the mold to a temperature of 120 to 160° C.

[0062] Now, one embodiment of the present invention in which alightweight cold polyurethane is produced by using the aforesaid threefluids A and fluid B is described below.

[0063] FIGS. 4 to 7 illustrate an embodiment of foam molding equipmentfor carrying out the process for the production of a lightweight coldpolyurethane in accordance with the present invention. In FIG. 4,reference numeral 1 designates a urethane foaming mold having an air bagtype mold clamping structure. This mold 1 is attached to a mold carrier2 positioned on a circuit conveyor line (not shown), and used to produceurethane foam (product) for automobile seats and others by injectingthereinto a urethane-forming raw material fluid 3 comprising foaming rawmaterials and allowing it to be foamed and cured therein. For thispurpose, a total of four fluids (i.e., three fluids A and one fluid B)are fed from raw material fluid sources (not shown) to an injection head6 by way of hoses 4 and 5, and the resulting urethane-forming rawmaterial fluid 3 is injected from injection head 6 into the lower moldsection which will be described later. Thus, fluids A and B are mixed bycollision in the injection head and then injected into mold 1. In thisfigure, only two hoses 4 and 5 are shown for purposes of simplification.Actually, one hose is provided for each of the four fluids.

[0064] As illustrated in FIG. 4, the aforesaid mold 1 is made up of anupper mold section 7 and a lower mold section 8 which are formed ofcasting aluminum (e.g., AC4C) and assembled in superposed relationship.These upper mold section 7 and lower mold section 8 are configured sothat, when they are assembled into mold 1, vacant spaces (cavities) forforming the product are left therein.

[0065] A large number of air bags 10 which can be inflated by pneumaticpressure are disposed at the bottom of lower mold section 8. Mold 1 isconstructed so that, when a dog 11 is kicked, these air bags 10 areinflated by filling them with air supplied from an air supply source(not shown). As a result, lower mold section 8 is raised to mate withupper mold section 7. Then, upper mold section 7 and lower mold section8 are sealed and locked together by means of a mold-locking clampcylinder.

[0066] On the other hand, a vent hole 13 extending through upper moldsection 7 and communicating with the vacant space within mold 1 isprovided at the center of upper mold section 7. Moreover, a vent valve(not shown) for opening and closing vent hole 13 is provided at thecenter of the outside of upper mold section 7. This valve can be movedin a vertical direction by means of an air cylinder (not shown) servingas an actuator. Depending on the vertical position of the valve in thevent hole, air within the vacant space is allowed to escape to theoutside of mold 1 through the gap between their mating surfaces. Thusthis valve is connected to the air cylinder.

[0067] The aforesaid air cylinder is controlled by an air sequencecircuit operating in response to the foaming rate of urethane-formingraw material fluid 3 (i.e., the rate at which the raw materials react tofoam and expand) so as to time the operation of the valve properly. Forthis purpose, an air sequence box 21 having the air sequence circuitincorporated therein is attached, for example, to one side of moldcarrier 2. As illustrated in FIG. 5, air sequence box 21 has a main airtube 22 and two sub air tubes 23 and 24, and these sub air tubes 23 and24 connect air cylinder 15 and air sequence box 21 with each other.Consequently, air is supplied from an air supply source (not shown) toair sequence box 21 through main air tube 22, and then supplied to theair cylinder through any one of sub air tubes 23 and 24 so as to movethe aforesaid valve (not shown) vertically.

[0068] Now, the process for the production of urethane foam (product)for automobile seats by use of urethane foaming mold 1 in accordancewith this embodiment is explained on the basis of process steps (1) to(7) shown in FIG. 6.

[0069] (1) Injection of Urethane-forming Raw Materials

[0070] First of all, a predetermined amount of urethane-forming rawmaterial fluid 3 is injected from injection head 6 into lower moldsection 8 of mold 1 in the state shown in FIG. 4.

[0071] (2) Mold Closing

[0072] After the injection of urethane-forming raw material fluid 3,mold 1 is closed by swinging upper mold section 7 toward lower moldsection 8.

[0073] (3) Locking of Upper and Lower Mold Sections and Starting of AirSequence Timer

[0074] By kicking dog 11 shown in FIG. 4, air bags 10 are filled withair to raise lower mold section 8. Thus, upper mold section 7 and lowermold section 8 are completely sealed and locked together by means of aclamp cylinder. Moreover, when dog 11 is kicked, the timer of airsequence box 21 is started.

[0075] (4) Closing of Vent Valve

[0076] Then, when the set point (defining the time at whichurethane-forming raw material fluid 3 foams and rises to the top ofupper mold section 7) of the timer of air sequence box 21 reaches apredetermined value (e.g., 3-20 seconds), a vent valve provided in uppermold section 7 is lowered and close vent hole 13. During this time, thefollowing two reactions take place in urethane-forming raw materialfluid 3 within mold 1, resulting in the formation of spongy urethanefoam.

[0077] (i) Polymerization reaction (formation of urethane linkages)

[0078] Polyol+Isocyanate→Urethane polymer

[0079] (ii) Foaming reaction

[0080] Water+Isocyanate→Carbon dioxide+Urea compound

[0081] (5) Unlocking of Upper and Lower Mold Sections and Opening ofVent Valve

[0082] By kicking dog 11, air is discharged from air bags 10 to droplower mold section 8, and the clamp cylinder unlocks upper mold section7 and lower mold section 8. Moreover, the air cylinder moves the ventvalve upward and vent hole 13 is opened.

[0083] (6) Removal of Product

[0084] In this state, mold 1 is opened by swinging upper mold section 7upward, and the product (urethane foam) is removed from mold 1.

[0085] (7) Application of Mold Release Agent

[0086] Thereafter, in preparation for the next production cycle, a moldrelease agent (comprising wax dissolved in a solvent) is sprayed overupper mold section 7 and lower mold section 8 of mold 1, and then driedto evaporate the solvent. Thus, the surfaces of mold 1 are coated withthe mold release agent.

[0087] When urethane-forming raw material fluid 3 foams, an internalpressure is applied to the inside of mold 1. If the vent valve is notprovided, upper mold section 7 may jump up when upper mold section 7 andlower mold section 8 are unlocked in step (5) shown in FIG. 6. Afterhaving jumped up, upper mold section 7 falls down under the action ofgravity. Then, upper mold section 7 may strike against the urethane foamproduct and cause damage thereto (this phenomenon is called “doublestamping”). Accordingly, the vent valve in accordance with thisembodiment is also effective in preventing such double stamping. Thatis, since the vent valve is opened in step (5) of FIG. 6, the internalpressure is released.

[0088]FIG. 7 illustrates one embodiment of equipment for the productionof lightweight backrests 84 for automobiles. On a circuit conveyor line72, a plurality of mold carriers 73 are disposed with fixed spacings.Each of these mold carriers 73 has the aforesaid urethane foaming moldsattached thereto.

[0089] In order to produce urethane foam (for example, for use inautomobile seats) by using these urethane foaming molds, an injectionrobot 74 injects the urethane-forming raw material fluid into the lowermold section of the open mold located at position A of FIG. 7. Then, amold closing device 75 closes the upper mold section of the mold atposition B. On circuit conveyor line 72, the mold carrier 73 travels ina clockwise direction as shown by an arrow in FIG. 7, and theurethane-forming raw materials within the mold are allowed to foam andcure during traveling. At position C, the upper mold section of the moldis opened and the product (e.g., a cured seat cushion) is removedtherefrom. In FIG. 7, reference numeral 76 designates a coating robotfor applying a mold release agent to the inner surfaces of the urethanefoaming molds.

EXAMPLE

[0090] Using the raw materials shown in Table 4 below, backrests oflightweight cold urethane were produced by means of a four-componentinjection head. TABLE 4 Compounding ratio (by Raw materials Manufacturerweight) Fluid A Polyol (PPG + POP) Asahi Glass 100 Co., Ltd.Crosslinking agent Mitsui 1.0 (diethanolamine) Chemicals, Inc. Catalyst(TEDA-L33) Tosoh 0.5 Corporation Catalyst Tosoh 0.08 (TOYOCAT-ET)Corporation Silicone foam Nippon Unicar 0.6 stabilizer (SZ-1311) Co.,Ltd. Silicone foam Nippon Unicar 0.9 stabilizer (L-5309) Co., Ltd. Foambreaker (DK Dai-ichi Kogyo 5.5 FLEX 800) Seiyaku Co., Ltd. Foaming agent(H₂O) 3.7 Fluid B Isocyanate (TM-20) Mitsui 45.0 Chemicals, Inc.

[0091] The ingredients except for polyol of fluid A corresponds to acomposition of auxiliary ingredients.

[0092] As the polyol, a combination of XF-8387 (trade name) and EL-946(trade name), both manufactured by Asahi Glass Co., Ltd., was used.

[0093] As the amine catalyst, a solution containing 33% oftriethylenediamine in 67% of dipropylene glycol was used.

[0094] As the silicone foam stabilizer, L-5309 (trade name),manufactured by Nippon Unicar Co., Ltd., was used.

[0095] As the water-soluble silicone foam stabilizer, SZ-1333 (tradename), manufactured by Nippon Unicar Co., Ltd., was used.

[0096] As the isocyanate, a mixture composed of 64% of 2,4-TDI, 16% of2,6-TDI, and 20% of MDI was used.

[0097] No rust preventive was needed.

[0098] The backrests so produced had excellent flame retardancy.Moreover, in spite of the fact that a four-component head was used forthe purpose of production, the piping could be prevented from rustingand the uniformed dispersion of auxiliary ingredients could be achieved.

[0099] Although the present invention has been described with referenceto the embodiments shown in FIGs, it is not limited to theseembodiments. All modifications, changes, and additions that are easilymade by a person skilled in the art are embraced in the technical scopeof the present invention.

[0100] The disclosure of Japanese Patent Application No.2001-141792filed on May 11, 2001 including the specification, the claims, thedrawings, and the abstract is incorporated herein by reference with itsentirety.

What is claimed is:
 1. A process for the production of a lightweightcold urethane, which comprises the steps of: adding diethanolamine tothe formulation in an amount of 0.1 to 2.0 parts by weight per 100 partsby weight of a polyol; and injecting raw materials into a mold in oneshot.
 2. A process for the production of a lightweight cold urethane asclaimed in claim 1 wherein principal raw materials including a polyoland an isocyanate, and an auxiliary ingredient mixture prepared bypreviously mixing auxiliary ingredients other than the polyol and theisocyanate, are each injected from separate storage vessels into a mold,and a water-soluble silicone foam stabilizer is added to said auxiliaryingredient mixture.
 3. A process for the production of a lightweightcold urethane as claimed in claim 1 or 2 wherein the raw materialsinclude 100 parts by weight of a polyol, an isocyanate used in an amountin the range of 70 to 150% of its stoichiometric amount for the polyol,and an auxiliary ingredient mixture comprising 2.5 to 5.5 parts byweight of water, 0.1 to 2.0 parts by weight of diethanolamine, 0.5 to 3parts by weight of a catalyst, 0.4 to 2.0 parts by weight of awater-soluble silicone foam stabilizer, 0 to 2.0 parts by weight of asilicone foam stabilizer, and other additives.
 4. A process for theproduction of a lightweight cold urethane as claimed in claim 2 or 3wherein said auxiliary ingredient mixture further comprises a rustpreventive.
 5. A process for the production of a lightweight coldurethane as claimed in claim 2 wherein said auxiliary ingredient mixturefurther comprises a polyol.
 6. A process for the production of alightweight cold urethane as claimed in claim 5 wherein a polyol isadded to said auxiliary ingredient mixture in an amount of 0 to 50 partsby weight per 100 parts by weight of the polyol fed to the mixing headas a principal raw material by way of another system.